FIGURE 4.

Light-dependent hydrogen production activity of HydA1 wild type and mutant proteins. The samples were prepared as described above. X1 and X2 indicate inactive control samples that lack either HydA1 or PetF. After incubating the reaction mixtures for 30 min in the light (1200 μmol photons × m⁻² s⁻¹) or, as a control, in the dark (shaded), the H₂ content of the gas phase was determined by gas chromatography. Chla, chlorophyll a; WT, wild type.